Data communication is an important function of many integrated circuits. For alternating current (AC) signals coupled to wireline communication systems, low frequency signals from a transmitter are filtered out by the AC capacitor, resulting in a dynamic common mode variation at a receiver. This variation is called baseline wander, and its magnitude depends on the bit pattern history, channel loss, and the time constant associated with the AC capacitor. If the input signal is not adjusted to compensate for the baseline wander, the received eye margin is reduced and bit error rate (BER) is increased.
Various baseline wander correction techniques have been implemented in the past. One adaptive technique involves passing the received history bits through an analog low pass filter or a digital infinite impulse response (IIR) filter, and subtracting the output from the received signal before detection. However, the bandwidth and the gain of these filters are difficult to determine, and adaptation of the bandwidth and gain parameters is challenging. Manual sweeping can be costly and time consuming, as the accurate values of the bandwidth and the gain depend on the transmitter and receiver settings, channel property and the process, voltage, temperature (PVT) variations of the channel, transmitter and receiver. Another adaptive technique uses the data crossing information for baseline wander correction. However, it requires a sampling rate of twice the speed of the data rate, and therefore consumes more power than baud rate sampling.
Accordingly, improved circuits and methods of receiving data in an integrated circuit are beneficial.